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Senior Xamarin Developer (Telecommute)

Lake Forest, CA, 92609
March 11, 2018

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Stephen Marcus


Xamarin Certified




Windows Phone

Dot Net


C#, with emphasis in UI Development

.NET Platform

Windows Communication Foundation


Windows Presentation Foundation


Visual Studio,

through 2017

Philosophy & Architecture

Agile development

Object Oriented Programming (OOP)

Object Oriented Design (OOD)

Dependency Injection

Inversion of Control

Composite Application Blocks

Service Oriented Architecture (SOA)


Database &


RESTful Services


MS SQL Server


Object relational mapping (ORM)

Component Libraries






Productivity & Teamwork Tools

GitHub / GitFlow

Team Foundation Server

Team City



IBM ClearCase and ClearQuest

Test Driven.Net


Tool for Application Developers (TOAD)





VBA (“Visual Basic for Applications”)

Visual Basic


Senior C# Xamarin / WPF

Software Developer


●Certified Xamarin Developer (2 years)

●Proven ability to create complex, powerful and versatile enterprise-level business applications on short-term deadlines, including design and architecture through programming, testing and support

●User Centric UI /UX design

●Object-oriented programming expert; 15 years with C#

●Expert in client-server technologies: WPF (8 years) and WinForms. This is the basis of mobile app development as well.

●LINQ, the Task Parallel Library (TPL), and all other C# core libraries

●Cloud-based data access using Azure, Amazon Web Services (AWS); RESTful web services

●Software development strategies, including AGILE

●Coding strategies: SOLID, MVC, MVVM (including frameworks), and design patterns

●Superb problem solving and troubleshooting

●Quality Assurance through Test Driven Development

●Flexible, effective communicator (and listener)

●Accustomed to tight deadlines and the need to set priorities in a high-pressure team environment


Certified Xamarin Cross-Platform Developer

Xamarin University: 2015, 2016, 2017

Mastered the entire 60-course curriculum relating to Xamarin and all of its mobile platforms: Android, IOS, Forms and Windows Phone

(The requirement was 17 courses).

Published Apps

Video Tran, on the iTunes store

The app is navigationless. Everything that happens occurs on the main stage.

The app is completely animated. All UI changes slide gracefully into place. There is no storyboard here, nor any other form of static development.

The app provides context-sensitive help to inform the user on what is happening, and what they can do.

The entire UI is 100% scalable. Tap the Settings icon and use the slider to change the size of all UI buttons and text. You can also increase or decrease all margins. The app actually does not contain any constant values for fonts, sizes, etc. Everything is relative to the portrait width of the device.

Professional Experience

Lighthouse 1/2018 – present

Senior C# Xamarin Developer

Designed and coded a complete consumer-facing app using Xamarin.Forms. The app allows end users to control their air purifiers.

Created a State Machine to handle changes in the app state. This in turn provided fine-tuned control over view and view model instantiation at run-time.

Managed communications using a combination of messaging (when more global) and events (when closely related).

Built a Mosquitto server listener so hardware devices could communicate with the app through spooled status reports.

Coded a Syncfusion graph to display changes in carbon dioxide, volatile organic compounds, particle mass, and related health conditions.

Built a scrollable sliding canvas that allowed views to scroll in from the eft or right in an elegant and contemporary fashion.

Implemented a dialog factory to provide consistent onscreen status reports and warnings.

Promoted code re-use through abstract classes and inheritance; polymorphism through interfaces and “var” style variables.

Websoft Developers 6/2017 – 12/2017

Senior C# Xamarin Developer

Created a complete app from scratch for a nationwide software firm so its clients –large municipal utilities – can manage their work crews more efficiently.

Implemented MVVM design pattern

Leveraged Autofac as the IOC container.

Created a custom offline strategy for loading and accessing the entire work database while disconnected; managed settings using a similar methodology.

Provided secure login using the corporate server; also allowed for session timeouts if the user remained offline for more than two days. In that case, their data was automatically refreshed.

Linked to REST services for data pulls and pushes via the Modern HTTP client and Newtonsoft.

Invented a custom UI control to display work orders in a tree format that gave users much better access to their work.

Amway 1/2017 – 6/2017

Senior C# Xamarin Developer

Took lead UI role in adding new features to an app for Amway’s cutting-edge line of consumer products.

Xamarin Forms focused with heavy MVVM.

Wrote middle-ware to connect to Amazon Web Services (AWS) using Refit interface declarations and supporting services.

Created local settings that synchronized to AWS using Xamarin. Plugins (Montemagno’s extension). I used the factory pattern to eliminate redundant code and to ensure reliability. These settings auto-synchronized to the cloud in the background (Task.Run).

Added push notifications using ACR.UserDialogs. Wired this so the app would respond from either cold-start or sleep whenever an error was received.

Implemented AutoFac IOC container using BeginLifetimeScope.

Converted universal time throughout the code base using NodaTime.

Added validation behaviors so the user was prevented from typing illegal characters into input fields; also validated upon ENTER key to verify that the entry was proper in its given context.

Designed interfaces to clarify the contracts between classes throughout the code base. Avoided passing implementations of classes.

Wrote extensions to centralize logic and prevent redundant coding.

Created Dependency Services for the device (orientation / screen width and height), keyboard, and pull-to-refresh.

Avoided unnecessary custom renderers; we only used a few. This makes the code much more manageable.

IMSA / Nascar 11/2016 – 2/2017

Senior C# Xamarin Developer

Debugged and reworked an existing app that was not working as expected. The app is used by attendees of Nascar events to watch the races and keep track of their favorite cars, drivers and teams,

Correctly implemented TPL calls such as Task.Run with callbacks, plus async/await where required.

Reduced source code size by 50% while improving reliability.

Eliminated code-behind; replaced this with MVVM and injected view models, which were stored in an Autofac IOC container. Used BeginLifetimeScope to constrain the lifetime of IOC variables.

Managed user profiles through Gigya.

Published Dependency Services for orientation and other device-specific features.

Created consistent PCL profiles for easier code distribution and sharing.

Established Crittercism / Apteligent crash logging throughout the app.

Verizon / Telogis 11/2016 – 12/2016

Senior C# Xamarin Developer / Trainer

Brought in on a short-term assignment as a coder, mentor and trainer to the existing staff.

Added new functionality to an existing Xamarin Forms installer app, including UI screens, offline data capabilities (using SQLite.Net), customized list views, and custom picker controls.

Created a dual bar code scanner to gather a bar code and a QR code simultaneously.

Made the app more user-friendly through “soft” features such as animations and visual cues.

Followed the MVVM design pattern; created view models; bound to commands; enforced notifications (INotifyPropertyChanged).

Verified and debugged the product(s) using unit tests and UI tests.

Q Mobile Integrators 12/2015 – 11-2016

Senior C# Xamarin Developer (IOS, Android and Forms)

Designed and coded full UI’s for a variety of client apps; added animations to keep the interfaces lively.

Created custom renderers and effects to allow for pixel-perfect platform-sensitive design under Xamarin Forms.

Leveraged MVC and MVVM design patterns.

Awaited services using the Task Parallel Library (TPL).

Managed security through OAUTH and encrypted passwords and pins.

Tested and debugged the product(s) for final user acceptance.

Xamarin University 10/2015 – 11/2015

Certified Cross-Platform Developer

for Android, IOS and Windows Phone

Rotary, Inc. 7/2015 – 10/2015

Senior C# WPF Developer

Cleaned up, debugged, and added new features to a WPF kiosk application for the company’s worldwide headquarters.

Major focus on animations, MVVM design pattern, image handling, and touch interface.

Varian, Inc. 9/2014 – 7/2015

Senior C# WPF Developer

Lead role in migrating 2 gigabytes of legacy code into a modern WPF application, including Injection of Control (IOC) container, Microsoft Entities, and full MVVM support.

The application manages industrial x-ray scanners that are used worldwide for airport security and hospital imaging departments.

Redesigned and refactored according to a more modern coding style, including focused class design, interaction through interfaces, and separation between the UI (view), business logic (view model) and data (model).

Fully implemented touch support, including flick, pan, zoom and tap.

Wolfram-Alpha 3/2014 – 9-2014

Senior C# WinRT 8.1 and Windows Phone 8.1 Developer

Designed and coded a unified solution for WinRT and Windows Phone 8.1 where 95% of the source was shared. The client is one of the world’s most renowned computer intelligence companies. They sell web services to provide instant problem solving for any type of business requirement. The apps promoted the firm’s new portable offerings.

WinRT and Windows phone are specialized coding environments with many tricks and twists when compared to WPF. Created elegant, centralized solutions that work safely in these exciting arenas. A few of the skills involved: MVVM, dependency properties, the event-driven model and emulator testing.


University of California, Santa Cruz

Bachelor of Arts in New Media

Graduated with honors.

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